This invention relates to the treatment of domestic and industrial wastewaters for the removal or reduction of organic or inorganic contaminants. Wastewater will move over zebra mussels that are attached to a fixed media (plastic, steel, concrete, etc.). The zebra mussels will filter the contaminates from the wastewater and incorporate them into their body mass, excrete them in their feces or encapsulate and excrete them in pseudofeces. The excreted feces and pseudofeces will be collected and periodically removed from the system.